The invention relates to a power distribution network cable fault wave head identification and positioning method and
system based on sheath traveling
waves, and belongs to the field of power
system relay protection. According to the invention, cable fault condition identification is carried out by adopting a sheath traveling wave
analysis method. The method comprises the following steps: carrying out identification and fault positioning on a power distribution network cable fault wave head by combining time-
frequency analysis with high-pass filtering based on traveling wave time-frequency characteristics of a cable sheath. Firstly, traveling wave measuring points are set at the head end and the
tail end of a cable sheath, transient information of the head end and the
tail end of the sheath during cable operation is recorded in real time, zero-sequence
voltage is set as a fault judgment quantity during cable fault, high-frequency transient quantity information of the cable fault is extracted for high-pass filtering, namely interference variables such as
noise and
harmonic waves in traveling
waves are removed, and the fault judgment quantity is calculated. For the traveling wave
signal after filtering
processing, each wave head information of the fault traveling wave is calibrated by adopting time-
frequency analysis, fault positioning is performed through position information of a fault initial wave head and each catadioptric wave head, a criterion is formed for cable fault positioning, the criterion is simple and reliable, the
coupling degree with an actual line is relatively good, and the selectivity and the sensitivity are relatively high.